South African Equine Veterinary Association Congress 2015 Protea Hotel Stellenbosch
exercise. However, as soon as the horse is deemed comfortable enough to walk, regular hand
walking for 20-30 minutes three to five times a week can be useful. In addition to burning
calories, exercise also improves tissue sensitivity to insulin and may further limit ongoing
lamellar damage.
Appropriate hoof care is also essential in horses with obesity-associated laminitis. Dietary
restriction and exercise may lead to desired weight loss but substantial lameness may persist if the
angle of the distal phalanx within the hoof capsule remains uncorrected by proper trimming and
possibly shoeing. Judicious use of non-steroidal anti-inflammatory drugs is also often required to
alleviate the pain of chronic laminitis.
Medications and supplements from managing EMS: There is a great desire for pharmacological
intervention in both human and equine metabolic syndromes; however, it remains unlikely that
there will ever be a “magic pill” for either weight loss or to markedly improve tissue insulin
sensitivity. Supplementation with thyroid hormone has been demonstrated to produce further
weight loss, as compared to diet alone, when overweight horses were administered twice the daily
recommended dose for a year. Next, potential benefits of metformin (15 mg/kg, PO, q 12 hours)
were demonstrated in 18 insulin resistant horses and ponies with laminitis. Results of insulin
sensitivity testing showed improvement within 1-2 weeks of starting the medication but the
improvement did not persist with long-term treatment and four patients continued to suffer
recurrent bouts of laminitis. However, no adverse effects of metformin were observed and the
relatively low cost of this drug makes it a likely candidate for further study. Unfortunately,
subsequent studies showed that metformin has poor bioavailability (around 5%) and have called
into question any benefits of this drug. However, recent evidence suggests that metformin may
actually work at the level of the gut to limit glucose uptake. Thus, blood concentrations of this
drug, reflected by bioavailability, may not be all that important.
Finally, it has been suggested that anti-oxidants might also be beneficial. Vitamin E can safely be
administered to horses at high levels (10,000 units, PO/day) but supportive data for improvement
in EMS are lacking. Currently, data that show therapeutic value for chromium, magnesium,
vanadium, or cinnamon supplementation for insulin insensitive horses are also lacking.
At present, prevention of obesity, especially in those breeds at greater risk for EMS, is the best
advice that is available and equine veterinarians should strongly consider assessing body weight
and fat stores (by using a weight tape or other measures to estimate weight and assigning a body
condition score) as part of their preventive care practices.
References
Equine metabolic syndrome and endocrinopathic laminitis - reviews
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Amer: Equine Pract 2002:18:271.
Frank N, Geor RJ, Bailey SR, Durham AE. Equine Metabolic Syndrome. J Vet Intern Med
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McGowan CM. Endocrinopathic laminitis. Vet Clin North Amer: Equine Pract 2010;26:233.
de Laat MA, McGowan CM Martin N. Sillence MN, Pollitt CC. Hyperinsulinemic laminitis. Vet
Clin North Amer: Equine Pract 2010;26:257.
Firshman AM, Valberg SJ. Factors affecting clinical assessment of insulin sensitivity in horses.
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Equine metabolic syndrome
Thatcher CD, Pleasant RS, Geor RJ, Elvinger F. Prevalence of overconditioning in
mature horses in southwest Virginia during the summer. J Vet Intern Med. 2012;26:1413.
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